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58 MIMICRY, AND OTHER PROTECTIVE 
dung. Kirby and Spence mention the small beetle 
Onthophilus sulcatus as being like the seed of an um- 
belliferous plant; and another small weevil, which is 
much persecuted by predatory beetles of the genus 
Harpalus, is of the exact colour of loamy soil, and 
was found to be particularly abundant in loam pits. 
Mr. Bates mentions a small beetle (Chlamys pilula) 
which was undistinguishable by the eye from the 
dung of caterpillars, while some of the Cassidz, from 
their hemispherical forms and pearly gold colour, re- 
semble glittering dew-drops upon the leaves. 
A number of our small brown and speckled weevils 
at the approach of any object roll off the leaf they 
are sitting on, at the same time drawing in their legs 
and antennz, which fit so perfectly into cavities for 
their reception that the insect becomes a mere oval 
brownish lump, which it is hopeless to look for among 
the similarly coloured little stones and earth pellets 
among which it lies motionless. 
The distribution of colour in butterflies and moths 
respectively is very instructive from this point: of 
view. The former have all their brilliant colouring on 
the upper surface of all four wings, while the under 
surface is almost always soberly coloured, and often 
very dark and obscure. The moths on the contrary 
have generally their chief colour on the hind wings 
only, the upper wings being of dull, sombre, and often 
imitative tints, and these generally conceal the hind 
wings when the insects are in repose. This arrange- 
ment of the colours is therefore eminently protective, 
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